Heretofore, a power slide door system has been known, which opens/closes a slide-type door mechanism provided in a vehicle by a drive force of a motor. This type of control device for opening/closing a vehicle slide door, which automatically opens/closes the vehicle slide door by driving the motor, is provided with a revolution number detection unit for detecting a revolution number of the motor. A technology of calculating a moving speed of the slide door based on a revolution number of the motor per predetermined time, which is detected by the revolution number detection unit, and of controlling the drive force of the motor, for example, a duty ratio in a PWM (Pulse Width Modulation) control based on the calculated moving speed of the slide door and a target moving speed is disclosed in Japanese Patent Laid-Open Publication 2000-127764.
In the technology described above, when the speed of the slide door is lowered more than a determining speed VJ, which is lower than a target speed VL by a predetermined value, the fact that a state where the speed of the slide door is lowered more than the target speed VL by more than the predetermined value (VL-VJ) continues is represented by a count of rotation pulse signals of the drive motor. Then, when the number of the counts reaches a value at which the above-described continuous state is determined, the duty ratio (d) of the drive motor is increased. A value calculated as an increment Δd is set relatively small, and for example, may be 2%. According to this disclosed technology, they say, by performing the above-described control, a radical increase of motor torque can be avoided even if pinching occurs, and the speed of the slide door can be made to coincide with the target speed irrespective of a load change.